1. Field of the Invention
The present invention relates to a data transmission system, and, more particularly, to a data transmission system which implements transmission and reception of data signals from and to electronic devices (nodes) including an information device.
2. Description of the Related Art
A fast serial data transfer interface based on the IEEE (Institute of Electrical and Electronics Engineers) 1394-1995 standards is recently receiving attention as an interface capable of transmitting data signals among a plurality of electronic devices. The IEEE 1394-1995 standards specify a plurality of information devices or nodes which are mutually connected by a serial bus and implementation of data transmission among plural systems of nodes in a time-shared manner. The standards provide a technology which facilitates realization of so-called home multimedia systems and home networks.
The IEEE 1394-1995 standards however impose the following restrictions.
(1) The maximum number of nodes connected in the system is 63. PA1 (2) A loop connection path is prohibited within the system. PA1 (3) The connectable upper hop count in the system is limited to 16 (the maximum number of nodes to be connected between one terminal node of the connection path and the other terminal node thereof is 17 including the two terminal nodes).
If a user connects 64 or more nodes to the bus, or employs a loop connection or connects 17 or more hops without considering such restrictions, the proper operation otherwise guaranteed by the IEEE 1394-1995 standards may not be expected. In such a case, bus stopping (hang-up) or malfunction of the bus may occur in the process of controlling nodes to the bus.
The IEEE 1394-1995 standards are adaptable to video cameras and audio products of non-professional or ordinary use and are applicable to a wide range of users. It is thus an urgent task to resolve the aforementioned shortcoming.